1. Field of the Invention
The present invention relates in general to a recording apparatus equipped with (a) a head unit including an actuator which generates energy required for recording predetermined patterns of image on a recording medium, (b) a circuit board including a driver element which drives the actuator, and (c) a heatsink disposed in thermally conductive communication with the driver element.
2. Discussion of Related Art
There is known a recording apparatus equipped with (a) a head unit including an actuator which generates energy required for recording predetermined patterns of image on a recording medium, (b) a circuit board including a driver element which drives the actuator, and (c) a heatsink disposed in thermally conductive communication with the driver element.
As an example of such a recording apparatus, JP-A-2002-240306 (the content of which is incorporated in U.S. patent application published as US 2002/0105567 A1) discloses an ink jet recording apparatus having head units. Each of the head units has a plurality of nozzles, a plurality of pressure chambers corresponding to the respective nozzles, and an actuator (piezoelectric actuator) for pressurizing an ink in each of the pressure chambers so as to deliver the ink from a corresponding one of the nozzles. The head units, together with a cover plate, is attached to a bottom face of a body frame. The head units,. except their respective portions in which the nozzles are open, are covered with the cover plate. The ink jet recording apparatus further has flexible circuit boards each of which has a driver element (driver circuit chip) mounted thereon and serving to drive the actuator. Each of the flexible circuit boards is connected with the actuator, and extends along the bottom and side faces of the body frame. Another cover plate. (lid plate) is attached to the body frame so as to cover the flexible wiring boards. The driver elements of the flexible circuit boards are pressed, by an elastic member (made of rubber or sponge) that is secured to the side face of the body frame, against the above-described another cover plate. Thus, the another cover plate serves as a heatsink for radiating or dissipating heat generated by activation of the driver elements which are held in contact with the another cover plate.
In recent years, as a result of provision of an increased number of nozzles with an increased density in the head unit, a wiring arrangement connecting the driver element and the actuator has become denser, and each wire of the wiring arrangement has become finer. Due to the denser wiring arrangement and the finer wire, signals fed through the wires tend to be easily affected by noises. It is therefore necessary to arrange the driver element and the actuator with a closer distance therebetween, so as to reduce length of each wire of the wiring arrangement. However, the increased number of nozzles leads to an increase in amount of heat generated by the driver element, and the increased amount of heat is easily transferred through the body frame or the heatsink, to the actuator which is positioned to be close to the driver element. With the actuator being heated by the heat, the actuator suffers from change in its actuation property (particularly, where piezoelectric elements are used in the actuator). With the ink being heated, physical property of the ink is changed. The changes in the actuation property of the actuator and the physical property of the ink cause deterioration in the quality of the printed image.